The theory of multilayer adsorption as proposed by Brunauer, Emmett and Teller3 has been applied extensively to physical adsorption isotherms. While the simple B. E. T. equation provides an excellent method of estimating surface areas," it usually holds only for relative pressures of 0.05 to 0.40. In almost every case the amount adsorbed at relative pressures higher than 0.40 is less than that predicted by the simple B. E. T. equation. This discrepancy has been explained in three ways: (a) by assuming the heat of adsorption in the second layer to be less than the heat of liquefaction of the adsorbate3Jf6; (b) by assuming that the structure of the adsorbent is such that it will permit adsorption to only a finite number of layers3; and (c) by considering the effects of capillary condensation.' Isotherms in which capillary condensation probably occurs as characterized by flattening of the isotherm at sufficiently high relative pressures and usually by strong hysteresis will not be considered in this paper.In studies of many isotherms involving the adsorption of a number of gases on presumably nonporous solids the author has observed that the simple B. E. T. equation can be fitted to the isotherms to relative pressures greater than 0.7 by multiplying the relative pressure by a constant that is less than one. In the present paper this constant is interpreted to h e a n that the heat of adsorption in the second to ninth layers is less than the heat of liquefaction. An .equation of a similar type for adsorption isotherms on porous solids and a, new type of equation for adsorption limited to n. layers have been derived.The isotherms used as examples were determined by conventional methods and the isotherms either have been described in the literature or will soon be published. Modified B. E. T. Equation with Heat of Adsorption in Second and Next Several Layers Less than the Heat of Liquefaction.-In the following derivations the assumptions and development are the same as those of the B. E. T.(1) Published by permission of the Director, Bureau of Mines, (2) Physical tChemist,.Bureau of Mines, Central Experiment Sta-(3) Brunauer, Emmett and Teller, out that changes of heat of adsorption in second and subsequent layers from the heat of liquefaction will cause the relative pressure to be multiplied by.a constant factor, and that for slight variations of this constant the linear plot of B. E. T. equation was not affected. (7) Brunauer, Deming, Deming and Teller, ibid., 61, 1723 (1940). U, S. Department of the Interior. tion, Piiitsburgh, Pa. Not copyrighted. 36; Emmett, I n d . Eng. Chcm., 37, 639 (1945).equation3 with the exception of the variation of the heat of adsorption in the second to ninth layers. One way that an equation containing such a factor as described in the introduction can be developed is to postulate that the heat of adsorption in the second to about ninth layer, EZ to 9, differs from the heat of liquefaction, EL, by a constant amount d, and that the heat of adsorption is equal to the heat of liquefaction i...

By 24 months, ankles treated with STAR ankle replacement (in both the Pivotal and Continued Access Groups) had better function and equivalent pain relief as ankles treated with fusion.

Fifteen centers for orthopaedic treatment of the foot and ankle participated in a prospective randomized trial to compare several nonoperative treatments for proximal plantar fasciitis (heel pain syndrome). Included were 236 patients (160 women and 76 men) who were 16 years of age or older. Most reported duration of symptoms of 6 months or less. Patients with systemic disease, significant musculoskeletal complaints, sciatica, or local nerve entrapment were excluded. We randomized patients prospectively into five different treatment groups. All groups performed Achilles tendon- and plantar fascia-stretching in a similar manner. One group was treated with stretching only. The other four groups stretched and used one of four different shoe inserts, including a silicone heel pad, a felt pad, a rubber heel cup, or a custom-made polypropylene orthotic device. Patients were reevaluated after 8 weeks of treatment. The percentages improved in each group were: (1) silicone insert, 95%; (2) rubber insert, 88%; (3) felt insert, 81%; (4)stretching only, 72%; and (5) custom orthosis, 68%. Combining all the patients who used a prefabricated insert, we found that their improvement rates were higher than those assigned to stretching only (P = 0.022) and those who stretched and used a custom orthosis (P = 0.0074). We conclude that, when used in conjunction with a stretching program, a prefabricated shoe insert is more likely to produce improvement in symptoms as part of the initial treatment of proximal plantar fasciitis than a custom polypropylene orthotic device.

Level III, retrospective comparative case series.

Level III, retrospective cohort study.

Background: Jones fractures commonly occur in professional athletes and operative treatment remains the standard of care in this patient population. In our clinical experience, an aggressive postoperative rehabilitation protocol for National Football League (NFL) players with an average return to play (RTP) between 8 and 10 weeks can have successful outcomes with few complications. The purpose of this study was to quantify RTP and rate of complications, including nonunion, refracture, and reoperation among a cohort of NFL players with operatively treated Jones fractures. Methods: Between 2004 and 2014, 25 consecutive NFL players who underwent acute Jones fracture fixation by a single surgeon were reviewed. Operative treatment for the majority of patients involved fixation with a Jones-specific intramedullary screw and iliac crest bone marrow aspirate with demineralized bone matrix injected at the fracture site. Additionally, our protocol involved the use of noninvasive bone stimulators, application of customized orthoses, and an aggressive patient-specific rehabilitation protocol. Patient demographics were recorded along with position played, seasons played after surgery, RTP, and complications. RTP was defined as the ability to play in a single regular-season NFL game after surgery. At the time of surgery, average age for all patients was 24.0 years and BMI 31.0. Results: Player positions included 8 wide receivers, 4 linebackers, 4 tight ends, 2 defensive tackles, 2 cornerbacks, 1 offensive tackle, 1 center, 1 tackle, 1 defensive end, and 1 quarterback. Seventy-six percent of players underwent operative fixation during their first 3 seasons. Forty-eight percent were diagnosed before or during their rookie (first) season. RTP was 100% for all players and 80% were still playing at time of publication. Three patients (12.0%) refractured and required revision surgery. Time until RTP was influenced by other variables and difficult to measure because many surgeries were performed early in the offseason. All 9 players who underwent surgery between July and October, and were therefore eligible to return to play in the same season, had an average RTP of 8.7 weeks (range 5.9-13.6). Conclusion: With an appropriately placed intramedullary screw and an aggressive rehabilitation protocol, early RTP was achievable with a low refracture rate in professional athletes. All NFL players in this series were able to return to play after surgery. We observed that these injuries were more likely to occur in the first 3 seasons of play and in wide receivers, linebackers, and tight ends. This at-risk subset of players may benefit from improved preventative measures. Level of Evidence: Level IV, retrospective case series.

Dorsal cheilectomy of the hallux metatarsophalangeal (MTP) joint through a medial approach can effectively provide long-term relief of pain and improve function in symptomatic mild-to-moderate hallux rigidus, despite progression of generalized first MTP joint arthritic degeneration and/or loss of motion. Fifty-seven patients (75 feet) with arthritis of the first MTP joint underwent dorsal cheilectomy through a medial approach for hallux rigidus failing nonoperative management. Excision of the dorsal articular surface of the first metatarsal head and dorsal osteophytes was performed through a medial approach that also allowed for plantar capsular release and removal of lateral osteophytes. Minimum follow-up was 3 years (average, 63 months; range, 37-92 months). Fifty-two patients (68 feet) returned for clinical and radiographic evaluation. American Orthopaedic Foot and Ankle Society Hallux Rating scores improved from a preoperative average of 45 to 85 points at follow-up. Average dorsiflexion improved from 19 degrees to 39 degrees, and the average range of motion improved from 34 degrees to 64 degrees. Preoperative radiographic grade of arthritic degeneration was grade I in 17 feet, grade II in 39 feet, and grade III in 12 feet; at follow-up, the radiographic grade was grade I in 2 feet, grade II in 26 feet, and grade III in 40 feet. Thirty-two feet worsened one grade, 6 feet worsened two grades, and 28 feet demonstrated no change (12 of 28 were grade III, preoperatively). A dorsal spur recurred in 21 feet, 9 of which were symptomatic. Complications included two superficial wound infections and four transient paresthesias of the hallux, all of which resolved uneventfully.

In patients requiring hindfoot or ankle arthrodesis, treatment with rhPDGF-BB/β-TCP resulted in comparable fusion rates, less pain, and fewer side effects as compared with treatment with autograft.